Process of making formaldehyde.



pnirnn STATES PATENT onmo n,

HEINRICH v a HocHs'rntrrE-R, OF consrnuon, GERMANY, ASSI GNOR T0 PERTH AMIBOY CHEMICAL won-Ks, or new YURK, n. Y., A cdn-ronarton or NEW JERSEY.

rnocnss or Maxine FOBEALDEHYDE.

No Drawing. Original application filed llanuary 9, 1

filed April 28, 1914.

To all whom it may concern: I Be it known that I, HEINRICH VON HOOH- s'rn'mnn, a subject of the Emperorrof Austria-l-Iungary, and a resident of the city of Constance, Baden, Germany, have invented certain new and useful Improvements in the Process of Making Formaldehyde, of which the following is a full, clear, and exact description. I

The present invention relates to the production of formaldehyde from methyl-alcohol by conducting the vapors of the latter together with an admixture of air over cer. tain contact substances or catalysts-and is a division of my application for which Letters Patent No. 1,100,076 issued June 16, 1914 was grantedto me..'

Copper is the catalyst usually employed for effecting the oxidation of methyl-alcohol into formaldehyde by means of air and re-.

cently silver also has been resorted to because of the better yield obtained by the employment of this latter metal.

n the endeavor to obtain a perfect yield, other factors affecting the yield, have been given close attention, such as the influence of the proportion of methyl-alcohol and oxygen relative to each other as well as the temperature of the process; the researchhas been extended to the influence exerted by the presence of nitrogen and water-vapor in the alcohol-air mixture, but no solution of the problem which gives the control of the process into the hands'of the operator, has

This assumption was extended and was later on substantiated by certain experi- Specification of Letters Patent. I

. Patented Sept. 8, 1914.

913, Serial No. 741,106. Divided and this application Serial No. 834,886.

ments which gave surprising results and although, at present, 1t satisfactorily explains the possible status of the reactions, it is by no means claimed that it'represents the only true cause of the successful working of the process as other factors, yet. unknown, may also contribute to the attaining of the purpose in view. Even if my assumption is correct, I cannot state specifically at present,

whether both of the reactions have an equal share in the outcome of the process. The above assumption, however, that two reactrons, s o diflerent in their character, might go on simultaneously and perhaps independently of each other, lead to the subsequent investigation of the question whether a single uniform substance was the best catalytic means to perform the two so greatly vary-- mg reactions, and it was believed that the employment of a lurality ofmetals &c. as .a "catalyst =might e of greater advantage than the use of exclusively one metal for this purpose, This logical conclusion was tested by experiments and was substantiated by most surprising results.

In practising my process I usually employ two metals in a system; it is still an open question as to which one of the two the specific eifect on the methyl alcohol-air mixture is'to be attributed; i. e. which of the two components of the system causes the oxidation or splitting off of hydrogen respectively, but this one fact clearly stands out,

viz.,-that a suitable selection of the compolyst, whereby, only a-moderate yield of formaldehyde is obtained.

If the conditions under which the copper process is carried on, are left unchanged and only the copper metal substituted by silver, a somewhat more satisfactory yield is obtained but still much less than the theoretical, whereas a substitution by a plurality of metals turns out a perfect yield. Such an association of metals as will allow the vapors to contact with each of the metals as individuals because the identity of each is not merged in that of the other, displaying such higher merits as a catalyst or the manufacture of formaldehyde from methyl alcohol is, for instance, the combination of silver and copper, or silver with a trace of any of the metals of the platinum group.

Further investigation along the line indicated by the facts disclosed above will easily disclose other metals each of which, combined with another metal or with a plurality of metals will produce a system displaying higher .Inerits as a catalyst than a single 1 metal.

Another example of making formaldehyde according to my process from a mixture of air and methyl alcohol vapor consists in conducting said mixture through a heated copper tube containing metallic'silver in any form suitable for the process.

Still another example consists in the employment of metallic silver. on which metallic rhodium has been precipitated, the combination thus obtained representing a system giving most satisfactory results and also demonstrating that the mechanical features of the system may be greatly varied without departing from the spirit of my invention.

In my Patent No. 1,100,076, I have claimed broadly a process wherein the catalyst comprises a plurality of catalytic substances 0r metals in any proportions or form.

What. I claim and desire to secure by Letters Patent 1 a 1. The process of making formaldehyde consisting in conducting a mixture of air and methyl alcohol vapor at a suitable temperature over a metal with which a metal of the platinum group is associated, the vapor mixture being caused to contact with each of said metals.

2. The process of making formaldehyde consisting in conducting a mixture of air and methyl alcohol vapor at a suitable temperature over metallic silver with which a metal of the platinum group is associated, the vapor mixture being caused to contact with each of said metals.

3.'The process of making formaldehyde consisting in conducting a mixture of air and methyl alcohol vapor at a suitable temperature .over metallic silver with which metallic rhodium is associated, the vapor mixture being caused to contact with each of said metals.

In testimony whereof I have signed this specificationin the presence of two subscribing witnesses.

HEINRICH VOIN HOCHSTETTER.

Witnesses:

DAVID KORNEL, MILO A. JEWETT. 

